Landfills
(Student Activities #5 and #6, Appendix D)
Where does trash go? Landfills are places that store trash. Landfills charge trash companies or individuals to store their trash. Originally landfills were merely huge ditches where the trash was piled. Modern landfills are designed to keep the trash from affecting the soil or aquifers from the trash stored above it by using plastic or clay liners to separate the trash from the ground. As the items in the landfill decompose, mainly food, or plant material, they produce both heat and liquid. This liquid then seeps through the rest of the trash. If the other trash has toxic chemicals, even paint, pesticides, fertilizers, or automobile oil, etc., the liquid carries this with it. The decomposition also produces CO2, which is water soluble and increases the acidity of the liquid. Then the liquid becomes more corrosive and so can add more toxins to it as it corrodes materials in its path. This problem, identified in the 1970's and 1980's as contamination called leachate, was reaching groundwater. However, the EPA estimated that more than 75% of the landfills in the United States, now, had escaping leachate. 1 0 In addition, most engineers admit that the liners installed today, will not last forever. The trash is divided into cells to separate a large landfill. The trash in the cells is regularly compacted and soil is bull dozed over it to bury it. By burying it and covering it with a cap to separate it from precipitation, the decomposition is minimized, since it is separated from water and oxygen.
In addition to the leachate, methane gas is produced from the decomposition, and modern landfills are required to monitor this since it is very flammable. The landfills collect the gas and either burn it or use it for heat. 4 Some scientists and environmentalists are worried about the collection of the methane gas. They believe that the methane gas has pollutants and carcinogens with it- thus making it extremely dangerous. However, landfills are actually given credit for the collection of the methane gas as a renewable energy source. No doubt, we should not be looking to landfills for renewable energy sources that are dangerous to our planet. 1 1 Landfills can get very large before they are considered full and closed. After closing, some landfills have become parks, with benches and playgrounds sitting high atop the buried garbage. Communities must monitor the ground below for additional methane gas as well as undue settling. Certain activities must be avoided to avoid breaking the ground into the area of trash.
Some landfills have burned the trash over the years. Regulations and laws have increasingly regulated this as well as the emissions from burning the trash. Some areas have been able to recapture some energy, (usually by heating water into steam) as usable energy. This is more common in Europe than the United States, where land is scarce. However, the decrease in landfills, there were 8,000 in the United States in 1988 and only 1,654 reported in 2005, may necessitate this more and more. 1 2 Why the decrease? Besides regulations and the burgeoning amount of trash, as areas where people live grow, resistance to landfills grows. No one wants a landfill next to their neighborhood.
What sort of trash is in a landfill? Almost everything disposed of used to be in the landfills; however, regulations have banned things such as biomedical wastes, and other hazardous products such as oil and paint. Although, that doesn't mean it isn't there. We all know people who slip these substances into their trash, either because of convenience or ignorance. Most of the volume of the landfills though, currently, is paper. The Garbage Project, in 1991, exhumed eleven U.S. landfills and found 50% of their volume was paper. 4 It has been estimated by the American Forest and Paper Association that for every ton of paper that is recycled, 3.3 cubic yards of landfill is saved. 2
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